Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
  • H04J3/16—Time-division multiplex systems in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted
  • H04J3/1605—Fixed allocated frame structures
  • H04J3/1611—Synchronous digital hierarchy [SDH] or SONET
  • H04J3/1617—Synchronous digital hierarchy [SDH] or SONET carrying packets or ATM cells
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J3/00—Time-division multiplex systems
  • H04J3/02—Details
  • H04J3/06—Synchronising arrangements
  • H04J3/062—Synchronisation of signals having the same nominal but fluctuating bit rates, e.g. using buffers
  • H04J3/0632—Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q11/00—Selecting arrangements for multiplex systems
  • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
  • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
  • H04Q11/0478—Provisions for broadband connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J2203/00—Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
  • H04J2203/0001—Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
  • H04J2203/0051—Network Node Interface, e.g. tandem connections, transit switching
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J2203/00—Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
  • H04J2203/0001—Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
  • H04J2203/0089—Multiplexing, e.g. coding, scrambling, SONET
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04J—MULTIPLEX COMMUNICATION
  • H04J2203/00—Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
  • H04J2203/0001—Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
  • H04J2203/0089—Multiplexing, e.g. coding, scrambling, SONET
  • H04J2203/0094—Virtual Concatenation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5619—Network Node Interface, e.g. tandem connections, transit switching
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5672—Multiplexing, e.g. coding, scrambling

Definitions

• the present invention relates to the use of inverse multiplexing in association with the
• ATM Asynchronous Transfer Mode
• SDH Synchronous Digital Hierarchy
• Inverse multiplexing adapts a serial data stream into multiple slower parallel streams for transport as shown in Figure 1, and the demultiplexer reverses the process, also allowing for possible differences in path length and propagation
• a spare path may provide 1 :n protection.
• ATM ATM inverse multiplexer
• ITU International Telecommunications Union
• AIMS are intended for use within an ATM network, providing .an economic
• PDH Plesiochronous Digital Hierarchy
• ATMs are expected to be implemented within ATM switches and the proposal is that they
• multiple 2 Mbit/s links are generally multiplexed up successively to 8 or 34 Mbit/s or 140 Mbit/s.
• ATM ATM inverse multiplexer
• AIMs are intended, among
• Such switches would typically have a number of port options, including 155 Mbit/s (SDH rate) and 34
• figure 5 shows ATM traffic at 8 Mbit/s being transported via 4 x 2 Mbit/s physical links, although the figure 4 could in principle be any integer figure.
• PDH includes the definition of an 8.448 Mbit/s rate, this rate is now little supported by product vendors, partly because it is not in turn
• Synchronous Digital Hierarchy (SDH) multiplexer including an Asynchronous Transfer Mode (ATM) inverse multiplexer
• the SDH multiplexer would typically be associated with ATM rate adaption as shown in Figures 7 and 8.
• the SDH multiplexer further includes means for converting between contiguous concatenation for 622 Mbit s and virtual concatenation.
• a corresponding inverse multiplexer for the complementary process would be needed at the far end of the data path and this could remain in its conventional position as shown.
• Figure 1 illustrates the principle of an inverse multiplexer
• FIG. 2 shows a block diagram of an ATM Inverse Multiplexer (ATM);
• FIG. 3 shows the use of an AIM in an ATM network
• Figure 3a illustrates the relationship between bandwidth and cost increments
• Figure 4 shows a block diagram illustrating the application of a conventional inverse multiplexer
• Figure 5 shows a block diagram illustrating the application of an AIM within an ATM switch
• Figure 6 shows a block diagram illustrating the application of an AIM within an SDH
• Figure 7 shows a block diagram illustrating the processes before and after the ATM function in the Figure 6;
• FIG. 8 shows the actions on ATM cells corresponding to the processes illustrated in
• FIG. 7 An ATM inverse multiplexer function should be placed within an SDH multiplexer, i.e. not an ATM product, as shown in figure 6, and associated with ATM rate adaption as
• a multiplexer such as the SDH one shown in figure 6 would generally use virtual parallel streams internally between the AIM and the normal SDH multiplexer function, i.e. such that those streams - of 2 Mbit/s for example - would typically be in the form of a single, multiplexed serial internal stream.
• AIM function within an ATM switch can typically be implemented in software, taking advantage of the switch's multiple PDH ports, its implementation in an SDH multiplexer could typically require additional hardware. Overall system cost savings should still occur because of the reduction in physical ports.
• an 8 Mbit/s payload for example would be mapped into 4 x 2 Mbit/s, each 2 Mbit/s in turn then being mapped into an SDH virtual container (VC) of
• the ATM payload could be mapped directly and more efficiently into each of the SDH VC-12, allowing some of
• VC-12 the nominal size of VC-12.
• the nominal size of a VC-12 is 2.304 Mbit/s and is used to carry "2Mbit/s" or 2.048 Mbit/s.
• ITU recommendation define the mapping of an ATM cell stream into various VC-n: e.g. VC-2, VC-3 and VC-4.
• SDH has defined within the concept of virtual concatenation, in which a number of otherwise independent VC-n are associated together purely by references stored in the SDH network management system. This may be done for example in order that they could be ensured of similar geographical routing to ensure propagation delays a group of VC-n, when used for AIM in the way described, could with advantage be managed as a virtual concatenation group.
• a set of m xVC-n would then be defined as "VC-n-mc"
• multiplexer carrying a variable payload with in the case shown is 8 Mbit/s, for consistency of illustration. Above 2 Mbit/s the next level in the accepted hierarchy of network interconnections for ATM transmission is 34 Mbit/s. The use of a single
• ports on an ATM switch is typically a severe design and cost constraint with low speed
• each card which carries 2 Mbit/s ports would typically carry 8 such ports and occupy the space of a card which could otherwise provide a 155 Mbit/s port, i.e. about 10 times as much traffic.
• special additional shelf designs can sometimes be provided within the ATM switch. In order to concentrate the traffic of many low speed ports into a single 155 Mbit/s port, they add significantly to cost and complexity.
• interpreting figure 2 AIMS can alternatively be employed between end users, thereby allowing a managed SDH transport network to route single ATM circuits or groups of them.
• this approach can emulate one of the key attributes of an ATM network, that of supporting flexible bandwidth allocation, in this case in multiplex of
• an SDH multiplexer plus its associated ALM could be included in the ATM switch, so that the interface between switch and SDH network would be at a rate of (N x) 155 Mbit/s.
• N x the capacity used in that interface would be in increments of VC-n, such as VC-12 etc.
• Conversion may be carried out, for example within an SDH multiplexer wherever located
• CBR Constant Bit Rate
• VBR Variable Bit Rate
• QoS Quality of Service
• the QoS is defined per Virtual Container (VC) or per Virtual Path (VP) which may embrace multiple VCs.
• the QoS includes a number of parameters, some potentially complex and policing to verify that the QoS is being met imposes complex requirements on both hardware and software in the telephone company network.
• the contracted PCR is less than the UNI bearer, i.e. the transport path - can support then after policing a bearer of lower capacity per corporation can be used to economise on
• Rate Adaption to a smaller bearer involves the deletion of idle cells.
• a bearer of almost arbitrary size can be synthesised by ATM inverse multiplexing, which
• the parallel channels may be at primary rate (1.5
• a simpler parameter than QoS may be defined to be assigned per UNI port - which may embrace multiple VP - and is associated particularly but not exclusively with the use of ATM inverse multiplexing into SDH.
• QoS will be managed at the VP level. Through each VP a corporation can choose to tunnel a quantity of Switched Virtual Circuits to its other sites. It is then up to the corporation to police its own SVC such that within a VP which is passed to the telephone company, no "greedy" SVC will launch so many cells that it prevents a fair share of capacity being available to other SVC. This policing function occurs within the Enterprise switch. If it should fail, perhaps because of
• delay -sensitive traffic such as CBR can be protected shaping
• UNI port i.e. its limiting PCR rather than configuring typically 6-12 QoS parameters for each of up to 356 VP upper port as allowed by the UNI definition in ITU.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Computer Hardware Design (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Time-Division Multiplex Systems (AREA)

Applications Claiming Priority (3)

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• 1996
  • 1996-03-04 GB GBGB9604619.8A patent/GB9604619D0/en active Pending
• 1997
  • 1997-02-25 AU AU18883/97A patent/AU715715B2/en not_active Ceased
  • 1997-02-25 WO PCT/GB1997/000521 patent/WO1997033398A1/en not_active Application Discontinuation
  • 1997-02-25 EP EP97905266A patent/EP0824808A1/de not_active Withdrawn
  • 1997-02-25 JP JP9531547A patent/JPH11504790A/ja active Pending
  • 1997-02-25 US US08/945,899 patent/US20020041604A1/en not_active Abandoned
  • 1997-02-25 CN CN97190131A patent/CN1181853A/zh active Pending
  • 1997-11-03 NO NO975055A patent/NO975055L/no not_active Application Discontinuation

Non-Patent Citations (1)

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